Metal assemblies have been greatly used during the past few centuries. As technology advances, the use of superior metals, alloys, and other construction materials, have allowed for the creation of sophisticated buildings and machinery. Residual stress in individual metal members of such metal assemblies directly affects their stability, strength, and durability.
For example, welding is thought to be one of the most important technological processes used in various industrial fields such as industrial engineering, aerospace industry, automobile industry, shipbuilding industry, among many others. Generally, welding involves the joining of two fusible materials, generally with an intermediate or filler material through the application of heat. There are many known processes for welding metallic objects such as shielded metal arc welding (SMAW), gas-metal arc welding (GMAW), flux-cored arc welding (FCAW), and submerged arc welding (SAW), to name a few.
During a typical welding process, the joined metal work pieces inherently encounter effects of shrinkage, phase transformations, intensification of corrosion, solidification cracking, residual joint restraint stresses, and the like. Residual weld stresses arise in the weld zone of the work piece and can possess the characteristics of premature joint or weld failure. The residual tensile stresses arising after welding exert a considerable influence on the ductility and strength characteristics of welded work pieces and enhancing or restoring these characteristics may permit the avoidance of welded joint failure. It is a usual practice to alleviate the stress through a stress relieving, thermal or vibratory process. However, common stress relieving processes require increased temperatures and subjecting the weldments to substantially high temperatures for extended periods of time. Other processes shake or peen the weldment after joining. These processes can be expensive and may not be practical for most welding situations.
Accordingly, it is believed that there are other methods where residual stress may be relieved from welded joints and other joining of structures. However, to date, a practical and cost efficient method continues to be sought which can reduce the effects of residual stress on metal assemblies.